$\dfrac{8}{10} + \dfrac{9}{100} = {?}$
Solution: The fractions must have the same denominator before you can add them. Rewrite $\dfrac{8}{10}$ as $\dfrac{80}{100}$ $\dfrac{80}{100} + \dfrac{9}{100} = {?}$ $ = \dfrac{89}{100}$